“Ionospheric sounding” is a technique used in telecommunication and radio science applications. It provides real-time data on high-frequency ionospheric-dependent radio propagation.
An ionospheric sounding system has a synchronized transmitter and receiver. The time delay between transmission and reception is translated into effective ionospheric layer altitude.
“Vertical incident” (VI) ionospheric sounding uses a collocated transmitter and receiver, and involves directing a range of frequencies vertically to the ionosphere and measuring the values of the reflected returned signals to determine the effective ionosphere layer altitude.
Current applications of ionospheric sounding systems fall into two categories. A first application is for support of operational systems, such as shortwave (HF) radio communications and over-the-horizon (long range, ionospheric reflection) radar systems. This support can be in the form of predicting propagating frequencies at given times and locations or providing of real-time data representing current conditions so that system operating parameters can be optimized. Another application is for scientific research to enable better prediction of ionospheric conditions and better understanding of plasma physics of the Earth's atmosphere.